Isotope separation



Jan. 8, 1952 w, PE NNEY 2,581,813

ISOTOPE SEPARATION Filed May 8, 1943 2 SHEETS-SHEET l wnuzssss: INVENTOR O Z WM Gay/0rd! R y/fey.

ATTORNE Jan. 8, 1952 w. PENNEY 2,581,813

ISOTOPE SEPARATION Filed May 8, 1943 2 SHEETS-SHEET 2 WITNESSES: lNVENTOR ATTORN .to cause separation between two isotopes.

Patented Jan. 8, 1952 UNITED STATES PATENT OFFICE 3 2,581,813 Iso'ror SEPARATION Gaylord W. Penney, Wilkinsburg, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 8, 1943, Serial No. 486,185

12 Claims.

My invention relates to electrical discharge Errm where H is the magnetic field strength; e the charge'on the ion; M the mass of the ion. If

the ion is subjected t the action of an alternating electric field in a plane perpendicular to the magnetic field, and having a frequency equal to f, the radius of the path continually increases with- Y out limit.

Certain of the chemical elements are found to be mixtures of isotopes; that is to say, to be made up of atoms having substantially identical chemical properties but having masses slightly different from each other. The separation of two isotopes of an element presents a problem of extreme diificulty.

If the two isotopes are given electric charges (for example, by depriving an atom of each of one electron, thereby transforming them into ions), Equation 1 shows that, because they have the same charge e but different masses M, they will have difierent resonant frequencies in any magnetic field of strength H. It is possible to show that if two bodies carrying equalelectric .charges but having slightly difierent masses are acted upon by a uniform magnetic field combined with an alternating electric field having divergent lines of force and a frequency which is intermediate between their natural frequencies,-

the lighter will experience a net electrostatic ,force tending to move it in the direction of con,- vergence of the electric field, while the heavier experiences a net electrostatic force in the divergent direction of the field. I have conceived a possibility of making use of these net forces In general, I make use of the above-mentioned forces by projecting ionized molecules of the two isotopes into a, combined magnetic andelectric field of the above-mentioned character in an electrical discharge vessel wherein I provide suitable arrangements for collecting the two isotopes.

Oneobject of my invention is, accordingly, to

provide an arrangement in which a combined magnetic and alternating electric field are employed to effect separation of isotopes.

Another object of. my invention is to provide an arrangement in which the isotopes of uranium may be separated from each other.

Other objects of my invention will become apparent upon reading the following description taken in connection with the drawings, in which:

; F'igure- 1 shows a view in horizontal section along line II of Fig. 2 of an electrical discharge device in which the principles of my invention may be utilized, and

Fig. 2 shows a view partly in elevation and .partly in section along the line II--II of Fig. 1.

I Fig. 3 shows a view in vertical section along line III-III of Fig. 4 of another embodiment of the principles of my invention.

Fig. 4 shows a view along the line IV--IV of Fig. 3.

Referring in detail to Figs. 1 and 2 of the drawing, I provide a vacuum-tight container I which may suitably be of sector shape and of insulating material, or may be of some metal, such, for example, as copper, in which insulators support a pair of substantially concentric electrodes 2, 3. Means (not shown) are provided for impressing an alternating voltage between the electrodes 2, 3through suitable in-leading conductors which are omitted from the drawing for the sake of simplicity. Adjacent theconcave side of the Y electrode 2 is provided a duct 4 of refractory material leading from an enclosure (not shown) in which the material containing the isotopes to be separated, for example, uranium, may be heated by any means wellknown in the art toa sufficient temperatureto produce a vapor of substantial vapor pressure. Aligned openings 5 and 6, respectively, in the wall of the duct 4 and in the electrode 2 permit this vapor to fiow into the. spacebetween the two electrodes 2, 3. The container I is preferably evacuated to such a degree as to prevent any deleterious collisions with molecules. For certain cases it will be found desirable, however, to maintain a substantial amount of a light gas, such as helium within the container l to promote ionization.

. Th container I fits closely between the poles of a direct-current or permanent magnet (showduces .a uniform magnetic field perpendicular to i the plane of Fig. 1 throughout substantially the entire space between the'electrodes 2 and 3.

vAdjacenteach end of the container I is in.-

a series of bafiles I2, I3 substantially parallel to the concentric electrodes and The'jpartitions I2, I3 leave passages between themthrough which the isotopic ions can move fro'm the central portion of the container 1 to the collectorelectrodes I, B. In front of the respectiv partitions I2, I3 and substantially parallel to the collector-electrodes I and 8 are positioned the conductors of grids I4, I5 which are provided with in-leading conductors (not shown) through the 'walls of the container I by which their potential may be fixed atwill; :This potential maysuitably be several thousandvolts negative relative to the above m ention'ed grids I 6 and I1, and-be the same as that of 'bailles I2, I3 and grids 9,"II. In" front of the grids III, I5 and substantially parallel thereto are provided a set of grids I6, II

which are likewiseinsulatingly supported "and provided with in-leading conductors (not shown) through the walls'of the container I sothat'their potential may be fixed'a't will. 5

Parallel to the upper and lower 'faces of the container I in the reg'ion between the grids I6, I1 are positioned a set of electron-emissive film merits I8, Ieprovided with in-leadingconductors (not shown) through the walls of the container I and insulatinglysupported so that their potential may be fixedat wills Usually their potential will be substantially the same as, or slightly positive to, thatofthe-ab'ove-mentionedgrids IB'and I'I. Paralleltoand instaggered relation to the filaments I8, "i9 "are provided the conductors of a pair oif'grids 2|, -22 insulatingly supported and providedwith in- -lea'di'ng conductors not shown) through the wallsbf thecontainer 'by which their'potential may be fixed at will. To illustrate by a specific instance the'grids 2| and 22"may'be made 300'volts' positive with respect to filaments I8,"I9. The mode of operation of the'above-'described structure in separating isotopes is as "i ollows; The isotopic atoms diffuse from the duct II through the openings 5 and 6 into the central portion of the chamber 1. "The potential dif*- ference of the gridsZI and 22 relative s filaments I 8 and I 9 is "made" sufiicientso-that electrons from the latter are accelerated enough so thata substantial number of the atoms is ionized. The electronsc'ongregate between grids 2| and 2-2 and attract thmore weighty positive ions to that region.' Both electrons and ions acquire velocities in the space traversed by the magnetic fieldun'der the influence of the electric field'between'electrode's 2'and 3. The charged ions'accordingly tend to move under the influence of the magnetic field in curved paths and, as previously statedjthe eilect of the divergent alternating electric field is to produce a net force on the lighter ions in the direction of the electrodes 2 and or the heavier ions in the direction offth el'ectrode..3. The presence of the magnetic ilel'd. causes the velocity in the direction o'f'thelast mentioned electric field to be transformed into 4 paths, as shown at 23 and 24, by which the respective isotopes are moved transversely to the alternating electric field toward the grids I6, II, the lighter isotope moving toward one set of the above-mentioned collector electrodes and the heavier isotope toward the other. The diameter of the spirals alternately increases and decreases as the'isotope moves toward the collector electrode.

The baffles I2, I3 will intercept molecules which move in straight lines, and will also intercept isotopic 'ions carrying twice the electron-charge, such doubly-charged isotopes being formed occasionally in the discharge.

'I'o'ill'ustrate the principles of my invention by a specific exa'ihpleQseparation isotopes of atoms having-a mass of'the order of 200 to 250 (such as uranium) would suitably use a magnetic field strengthof the order of 10,000 gausses; the alternating electric field of the order of one volt per 'cm. and a frequency of the order of 65,000 cycles per second.

Referringto the modification of my invention shownin'liigs. 3 and a vacuum type container I of the "-same'g'ener'al type'a's'that previously described in'connection with Figs. 1 and 2 corntains a pair of substantially parallel plates 2 and '3 which are insulatingly supported, the plate numbered 2 being considerably shorter than the plate numbered The plates 2 and 3 perform a functicn'very similar to'that already'descrlbed in connection withthe' similarly numbered electrodes 2 and 3 in Fig.1 but differ from the latter in that while producing a divergent electric field the plane of divergence of this field is parallel to the lines of force of the magnetic' field instead of perpendiculanthereto' as in the Fig.1 modification. In other words',the plane of divergence of the electricfield betweenthe electrodesi and 3 is normal'tothe paper in Fig. 3 and "parallel to "thexplane of the paper in" Fig. 4.

Adjacent the two diverging sides of the casing I in '4 are positioned "the poles of a'direct current electromagnet (not shown) which producesamagnetic held in the plane of Fig. 4 in the s'pa'cebet'ween theelectfocles z'and 3. A duct 'l 'slmilarto that already described in Fig. i'is provided which leads from an enclosure (iiot' shown) from which vapors of tlie'm'aterial co n taining the isotopes tobe separated is heated, the Vapor flowing through the duct 4 and through the opening 5 in the electrode 2 upward into the space between the-electrodes 2 aud t. A pair'of collectorelectrodes I and fl'a'nalogous to "thg'v electrodes of the same number in Fig.- lare insulatingly s'upported'parallel to the endscf tiie enelo'sure I, and these are provided with in-leadingwiresanalogous to those already de-' scribed "for the Fig. "l modification. Parallel to the electrodes I, dare positioned the conductors 9; llfoi, apair of grids which are'analogous to and'pr'ovidedwith ni -leading wires (not shown) similar to ihegrids 9 and II already described ihT'iQgI 1 Immediately in frontof the grids 9 and II are insulatingly supported a series of lfraifies I2, I3 analogous'to the bafile's of the same numberin'Fig. 1. are "positioned 'the conductors of grids I4, I5 whichf'are's'imilar in 'ruueuon and provided with similar 'in-'leadirig conductors to those of the siniila'rlyfnumbered grids in Fig. 1. In front of theg-rids I I, wand substantially parallel 'theretti are-provided asecond'set 6f grids I6, I! provided with inleading'conductors" (not shown) so that theirpote'ntial may "be fixed at will and in a Infront of the bafiles I2, I3

manner similar to thatof the grids l8, IT in Fig. 1.

Insulatingly supported parallel to the slanting walls of the container l are positioned a pair of end partitions 3|, 32 which tend to retain the vapors entering through the opening 5 to the central region of the container I. Supported by insulators 33, 34, 35 on the end plates 3| and 32 are the parallel electron emissive filaments l8, 19 provided with in-leading conductors (not shown), the function of the filaments I8, 19 being similar to those of the similarly numbered filaments in the Fig. 1 modification. Parallel ,to .the filaments I 8, l9 and more remote from the partitions 3|, 32 are insulatingly Supported the conductors 2|, 22 of a pair of grids. The potential and function of the grids 2|, '22 are similar to those of the similarly numbered grids in Fig. l.

' The mode of operation of the Fig.3 modification will probably be evident to those skilled in the art from the preceding description of, the l modification. 'Molecules of the isotopes traveling out of the orifice 5 will be ionized by collision with electrons emanating from the thermionically emission filaments I8, l9. These ions will then move underthe impulse of the electric field between the electrodes 2, 3; will beacted upon by the magnetic field within the container I, and the heavier'isotopesfwill move toward one of the collector electrodes such as I while the lighter isotopes move toward .the other collector electrode 8. The function ofthe baffles 12,13 andthe grids 9, I], I4, .15, l6, I1 is similar in the Fig. 3 modification to the functions already described for the similarly numbered elements in Fig. l. The values of the electrical quantities described in connection with Fig. 1 apply also to the Fig. 3 modification.

I claim as my invention:

1. In an electrical discharge device, means for producing a substantially uniform direct-current magnetic field, means for producing an alternating divergent electrical field substantially at right angles thereto, means to furnish ions to the space occupied by said fields, and a collector electrode adapted to receive said ions moving through said field.

2. In an electrical discharge device, means for producing a substantially uniform direct-current magnetic field, means for producing an alternating divergent electrical field substantially at right angles thereto, means to furnish ions to the space occupied by said fields, a collector electrode adapted to receive said ions moving through said field, and means to produce a direct-current field substantially perpendicular to said alternating field and said magnetic field.

3. In an electrical discharge device, means for producing a substantially uniform direct-current magnetic field, means for producing an alternating divergent electrical field substantially at right angles thereto, means to supply atoms to the space occupied by said fields, an electron emitter and an electrode positive relative thereto adapted to cause ionization of said atoms, and means to produce a direct-current field substantially perpendicular to said alternating field and said magnetic field.

4. In an electrical discharge device,,means for producing a substantially uniform direct-current magnetic field, means for producing alternating divergent electrical field substantially at right angles thereto, means to supply atoms to the space occupied by said fields, an electron 6 1 emitter and an electrode positive relative thereto adapted to cause ionization of said atoms, a collector electrode and means for maintaining it substantially at the potential of said electron emitter, and means to produce a direct-current electric field perpendicular to said alternating field and said magnetic field.

5. An electric discharge device comprising means to produce a substantially uniform directcurrent magnetic field, a pair of electrodes substantially different in size and means to produce therebetween an alternating electric field substantially perpendicular to said magnetic field, means to supply atoms to the region occupied by said fields, an electron emitter and an electrode positive relative thereto adapted to produce an electronic discharge inthe region occupied by said atoms, means to produce a direct-current electric field substantially normal to said magnetic field and said alternating field, and a collector electrode positioned to receive electrified particles moving in response to the last-mentioned electricfield. v 6. Anisotop'e separating apparatus comprising means fo r producing a substantially uniform direct-current magnetic field, means for producing analternating divergent electric field substantially normal thereto, means to furnish ions to the region occupied by said magnetic and electric fields, means to produce'a directcurrent electricfield substantially normal to said magnetic field and said alternating'field, and-a collector electrode positioned to receive ionsmoving under influence of the last-mentioned field.

'7. An isotope separating apparatus comprising .means for producing a substantially uniform direct-current magnetic field, means for producing an alternating divergent electric'field substantially normal thereto, means to supply atoms to the region occupied by said fields, an electron emitter and an anode positive thereto for causing ionization of said atoms, means to produce a direct-current electric field substantially normal to said magnetic field and said alternating field, and a collector electrode positioned to receive ions moving under influence of the both fields.

8. An isotope separating apparatus comprising means for producing a substantially uniform direct-current magnetic field, means for producing an alternatin divergent electric field substantially normal thereto, means to supply atoms to the region occupied by said fields, an electron emitter and an anode positive thereto for causing ionization of said atoms, means to produce a direct-current field substantially normal to said magnetic field and said alternating field, and a collector electrode positioned transverse to the last-mentioned field and means for maintaining it near the potential of said electron emitter.

9. An isotope separating apparatus comprising means for producing a substantially uniform direct-current magnetic field, means for producing an alternating divergent electric field substantially normal thereto, means to supply atoms to the region occupied by said fields, an electron emitter and an anode positive thereto for causing ionization of said atoms, a grid electrode having its plane substantially parallel to said magnetic field and said alternating field, means to impress on said grid electrode a substantial negative potential relative to said electron emitter, and a collector electrode substantially parallel to said grid electrode and and means for maintaining said collector electrode substan- .7 tlaily at the potential of said-electron, emitter.

i di e separatin appa at s compr s'-' ingmeansifor producing asubstantially uniform direct-current'magnetic field, means for producing .an alternating divergent. electric field substantially normal thereto, means to supply atoms to the region occupied'by said fields, an electron emitter and an anode positive thereto for causingionizationofsaid atoms,ra grid electrode having its plane substantially parallel to said ma netic field and said alternating field, means to. impress on said g-ridelectrode .a substantial negative potential relative't'o said electron emitter, a colleotorelectrode substantially parallel to said grid electrode and means .for.maintaining said collector .electrodesubstantially at the potential of said electron emitter, .and'baffies located between .said grid electrode and said collector electrode and substantially normal to saidgrid electrode,

11. In an isotope separating device, means for producing av substantially uniform direct-current magnetic field, a smaller electrode rand .a larger electrode adapted to ,producea divergent halternating-electric field substantially .normal to said magnetic field, a gaseous atmosphere between said electrodes, an electron emitter and an anode positive thereto adapted .to produce an electronic discharge through said gaseous atmosphere, perforate electrodes provided with means for im pressing anelectricalpotential between them'and said. electron emitter land positioned to produce an electric field substantiall normal to said magnetic andsaidalternatingfield, anda collector electrode substantially parallel to said periorate electrodes and provided :with means for maintaining itsubstantially at the potential of said electron emitter.

12. In an..isotope separatin vi er m -10 producing a substantially uniform direct-current magnetic field, a-smaller electrode and a'larger electrode adapted to produce a divergent alternating-electricfiem substantially normal to said magnetic field, a gaseous atmosphere between said electrodes, an electron emitter and an anode positive thereto adapted to produce an electronic discharge through said gaseous atmosphere, perforate electrodes provided with means for impressing electrical potentials between them and said electron emitter and positioned to produce an electric field substantially normal to said magnetic and said alternating field, a collector electrode substantially parallel .to said perforate electrodes and provided with'means for maintaining it substantially at the potential of said electron emitter, and curved bafiles positioned between said perforate electrode and said collector electrodeand, having intervening passages between them substantially parallel to the path of a singlycharged atom of said gaseous atmosphere moving under the combined influence of said magnetic field and'the last-mentioned elec tric field.

GAYLORD W. PENNEY.

REFERENCES CITED The following references are of record in the file of this patent: V

UNITED STATES PATENTS 

